U.S. patent number 4,162,119 [Application Number 05/852,859] was granted by the patent office on 1979-07-24 for fiber optic position indicator.
This patent grant is currently assigned to International Telephone and Telegraph Corporation. Invention is credited to David S. Goodman.
United States Patent |
4,162,119 |
Goodman |
July 24, 1979 |
Fiber optic position indicator
Abstract
A fiber optic device for providing a visual indication when a
subassembly, such as an electronic "ATR box", is in place in a rack
mounting arrangement with its electrical connections firmly mated
with the corresponding rack connections within a small
predetermined tolerance. A special fiber optic connector has first
and second parts, one of which is attached to the ATR box and the
other mounting in the rack for mating concurrently with the mating
of the electrical connections. A number of such devices may be
provided in a rack of equipment, each fixed rack mounted connector
being supplied with a light signal via a length of fiber optic
conductor, preferably from a common light source. Within the ATR
box unit itself, another length of fiber optic conductor connects
the fiber optic connector to the front panel or some other location
for convenient observation. In one of the mating connector parts, a
slit diaphragm prevents any appreciable transfer of light between
the optical fibers of the connector parts until said diaphragm is
penetrated and deflected by the opposing optical fiber during the
last relatively small increment of movement into the mating
operation.
Inventors: |
Goodman; David S. (Mission
Viejo, CA) |
Assignee: |
International Telephone and
Telegraph Corporation (New York, NY)
|
Family
ID: |
25314416 |
Appl.
No.: |
05/852,859 |
Filed: |
November 18, 1977 |
Current U.S.
Class: |
385/60; 340/641;
385/73 |
Current CPC
Class: |
G02B
6/3849 (20130101); G02B 6/3897 (20130101); G02B
6/3873 (20130101) |
Current International
Class: |
G02B
6/38 (20060101); G02B 005/14 () |
Field of
Search: |
;350/96.20,96.21,96.22
;362/32 ;250/227 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Bedgood et al., Electrical Communication, vol. 51, No. 2, Feb.
1976, Demountable Connectors for Optical Fiber Systems..
|
Primary Examiner: Corbin; John K.
Assistant Examiner: Levy; Stewart
Attorney, Agent or Firm: O'Neil; William T.
Claims
What is claimed is:
1. A device for indicating the connected-in-place condition of a
physically removable subassembly having electrical connections
intended to make and disengage with and from fixed electrical
connections in a mounting arrangement in response to corresponding
translational movements, comprising;
a first fiber optic light conducting element mounted in
substantially fixed relationship with said removable subassembly,
said element having a first end arranged with respect to a part of
said removable subassembly to facilitate visual observation of
light emitted therefrom when said device is in said
connected-in-place condition in said mounting arrangement, the
second end of said element being oriented to receive light from an
external point along a light path substantially parallel to said
translational movements when said subassembly is in said
connected-in-place condition;
second means comprising a source of light and means fixed with
respect to said mounting arrangement for directing light along said
parallel path from a fixed location aligned with said first fiber
optic element second end;
and third means operative as a function of the axial spacing along
said parallel path between said fixed location and said fiber optic
element first end to prevent substantial light transmission through
said optical spacing when said axial spacing is less than a
predetermined amount corresponding to said connected-in-place
condition of said subassembly, and otherwise to permit light
transfer between said first fiber optic element and said second
means.
2. A device according to claim 1 in which said second means
includes a second fiber optic light-conducting element connected at
a first end to said light source, the second end of said second
fiber optic element being placed at said aligned location.
3. A device according to claim 2 in which said mounting arrangement
comprises a plurality of positions each having corresponding fixed
electrical connections for receiving a corresponding plurality of
removable subassemblies and in which each of said positions has a
corresponding one of said aligned locations at which a
corresponding second fiber optic element terminates, and in which
the corresponding plurality of second fiber optic elements thereby
provided are responsive to said source of light at their first
ends.
4. A device according to claim 1 in which said third means
comprises a flexible, substantially opaque diaphragm placed in said
light path a relatively small predetermined distance from said
second end of said second fiber optic element, said diaphragm being
adapted to admit said first fiber optic element at said second end
thereof, thereby to establish continuity of light transmission
between said first and second fiber optic elements beginning as
said translational movement during said mating reaches said
diaphragm and deflects it sufficiently to establish said continuity
of light.
5. A device according to claim 2 in which said third means
comprises a flexible, substantially opaque slit diaphragm placed in
said light path a relatively small predetermined distance from said
second end of said second fiber optic element, said diaphragm being
adapted to admit said first fiber optic element at said second end
thereof, thereby to establish continuity of light transmission
between said first and second fiber optic elements beginning as
said translational movement during said mating reaches said
diaphragm and deflects it sufficiently to establish said continuity
of light.
6. Apparatus according to claim 3 in which said ight source
includes means for transmitting of light of substantially the same
intensity into each of said plural second fiber optic element first
ends.
7. Apparatus according to claim 2 further comprising first and
second mating fiber optic connector bodies housing the
communicating ends of said first and second fiber optic elements,
respectively, said first connector body being mechanically fixed at
said removable subassembly and said second connector body being
mechanically fixed at said aligned location associated with said
mounting arrangement, said connector bodies mating concurrently
with mating of said subassembly and fixed electrical connections to
bring said fiber optic members into light-transmitting
relationship.
8. Apparatus according to claim 4 further comprising first and
second mating fiber optic connector bodies housing the
communicating ends of said first and second fiber optic elements,
respectively, said first connector body being mechanically fixed at
said removable subassembly and said second connector body being
mechanically fixed at said aligned location associated with said
mounting arrangement, said connector bodies mating concurrently
with mating of said subassembly and fixed electrical connections to
bring said fiber optic members into light-transmitting
relationship.
9. Apparatus according to claim 7 in which said connector bodies
have axial bores for receiving said corresponding fiber optic
elements and lateral alignment means operative during said mating,
in which said bodies each has an enlarged diameter bore with an
internally threaded portion and a gland nut engaging said threads
at its nonmating end, and in which a gland seal arrangement holds
said optical fiber elements in concentricity within said
bodies.
10. Apparatus according to claim 9 in which said flexible diaphragm
is mounted within the one of said bodies containing said second
fiber optic element adjacent its mating end, said gland seal
exerting axial force for position adjustment of said fiber optic
element within the corresponding gland nut to establish said
relatively small predetermined distance of said iris from said
second fiber optic element.
11. A connector structure for fiber optic cables comprising:
a socket body housing and holding an end of a first fiber optic
cable in generally axial position within said body;
a pin body housing and holding an end of a second fiber optic cable
in an axially protruding position, said pin and socket bodies being
matable to bring about abutment of said cable ends in a
light-transmitting relationship;
and resilient shuttering means associated with said socket body and
interposed between said cable ends for preventing the establishment
of said light-transmitting relationship until said end of said
second fiber optic cable penetrates said shuttering means
corresponding to a predetermined degree of axial mating of said pin
and socket bodies.
12. Apparatus according to claim 11 in which said shuttering means
includes a substantially opaque slit diaphragm of resilient
material.
13. Apparatus according to claim 12 in which said resilient
material is a polymer having relatively rapid resilient recovery
characteristics.
14. Apparatus according to claim 12 in which said resilient
material is one selected from the group of the flexible relatively
soft materials including rubber, synthetic rubbers and soft
plastics.
15. Apparatus according to claim 12 in which said diaphragm is
generally disc shaped and said slits are at least three in number
extending radially outward from the center of said disc and are
substantially uniformly spaced angularly about said center.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the field of interlocks and position
indicators, particularly those employing optical techniques.
2. Description of the Prior Art
In the prior art, a number of situations exist in which it is
desired to confirm, visually or otherwise, the engagement or
placement of a subassembly or unit in a rack or mounting
arrangement. Typical of such a requirement is the commercial
airliner situation in which a standardized rack mounts and provides
for the connection of various electronic subassemblies such as
radio communication and intercom equipment, navigation equipment,
and the like.
The commercial airlines, through an industry-owned organization
called "ARINC" have established so-called ATR standards for unit
sizes, standardized electrical connections and mounting interface
hardware. The term, LRU, refers to the lowest or least (smallest)
replaceable unit in such an arrangement. When these LRUs are
installed in an equipment rack, or removed and replaced for any
reason, it is important that there be some readily identifiable
indication that the unit is indeed fully and completely in place,
so that the electrical connection of the subassembly are reliably
mated to corresponding fixed connections in the mounting
arrangement. Such arrangements for that assurance have sometimes
been called "interlocks".
An interlock, or position-indicating arrangement or device, can
obviously be provided by a mechanical means and also can be purely
electrical, i.e., in which an electric switch is actuated or
deactuated when the unit is slid into place. Reliability and cost
considerations are obviously important. Purely mechanical devices
are relatively expensive and are subject to wear, maladjustment or
outright malfunction. Electric switches under all circumstances
including shock and vibration and other adverse environmental
factors leave much to be desired from the point of view of
reliability and fail-safety.
In electrical systems, there is always some inherent fire and
explosion hazard in addition to the other problems
aforementioned.
The manner in which the present invention deals with the
disadvantages of prior art approaches to the problem of reliable
electrical subassembly engagement indication will be understood as
this description proceeds.
SUMMARY
It may be said to have been the general objective of the present
invention to provide a position or engagement indicator for use in
applications of the type hereinbefore described, such device being
inexpensive, reliable, fail-safe, free of fire and explosion
hazards, and inexpensive to manufacture.
In the typical electronic equipment rack, such as that in
accordance with ATR standards, a plurality of individual
subassemblies comprising such devices as radio transmitters and
receivers, electronic navigational equipment, autopilot control
devices and the like are individually installed and individually
and discretely removable from their rack positions. During
installation or replacement, a sliding or translational motion
toward the back of the rack effects mating or engagement of the
electrical connectors on the removable or replaceable unit with
those on the rack or mounting structure. Suitable guide rails are,
of course, involved.
The present invention contemplates the placement of the halves of a
fiber optic connector assembly in mating relationship (i.e., one
affixed to the rack structure and the other to the removable
subassembly). The fiber optic connector employed in the combination
of the present invention is unique of itself, although it does rely
on some prior art structures and techniques in the fiber optic
connector art. The novel features of the connector structure will
be understood and appreciated as this description proceeds.
In particular, a relatively opaque, flexible slit diaphragm is
installed in one of the fiber optic connector halves which may be
thought of as the receptacle and acts as shuttering means. This
flexible diaphragm substantially shields the end of the optic fiber
axially adjacent to it from light transmission. When the other
connector, which is mounted on the removable subassembly, is mated
to its receptacle connector, an opposing protruding optical fiber
member thereon penetrates the diaphragm and comes into substantial
abutment with the optical fiber of the rack-mounted,
receptacle-type connector member.
The system of the invention may be employed with only a single rack
position and corresponding removable subassembly, however, it is
anticipated that all rack positions in a given mounting arrangement
would be equipped with the fiber optical receptacle connector
members disposed to be engaged to the connector mating member
corresponding to each removable subassembly for each such position
in the rack, Each of these receptacle connectors is energized by a
light signal conducted through its associated fiber optic cable
from a light source which preferably also includes a distributor
for substantially equalizing the light intensity in each of these
fiber optic cables.
The pin-type connector member associated with removable subassembly
as aforementioned has an associated fiber optic cable leading to a
position on the subassembly, such as its front panel, from where
the illumination resulting from substantially complete engagement
of the subassembly into the rack connectors can be confirmed
visually.
The details of the structure and other aspects of the system
according to the present invention will be evident as this
description proceeds.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a semi-pictorial type drawing of a typical arrangement
according to the invention.
FIG. 2 is a pictorial of a pair of typical matable fiber optic
connector elements adapted to the arrangement of FIG. 1.
FIG. 3 is a cross-sectional view of the connector elements of FIG.
2 in the mated condition according to FIG. 1.
FIG. 4 depicts the flexible iris (slit diaphragm) also shown in
FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1, a typical rack-mounting arrangement 1 is
depicted showing a typical pair of removable/replaceable
subassemblies 7 and 8. Numerals 34 and 35 represent assumed typical
locations for electrical connectors with subassembly 7, these
connectors comprising fixed rack-mounted connector sockets and
subassembly-mounted mating pin-type connectors, for example. As a
unit is installed or removed, these connections are automatically
made or broken, respectively. A corresponding pair of fiber optic
connector mating units 10 and 11 is shown, 10 being carried by the
subassembly 7 and 11 being the rack-mounted counterpart. The mating
of these parts 10 and 11 will be described in more detail
hereinafter, but for the sake of FIG. 1, it is sufficient to point
out that fiber optic connector 10 mates into 11 as the electrical
connectors at locations 24 and 35 are mated. Each rack-mounted
fiber optic connectors, such as 11, has an associated fiber optic
conductor or cable (element), namely that represented at 4, in
connection with 11. Cables 5 and 6 represent two additional fiber
optic conductors for other subassemblies in the rack arrangement,
it being understood that ordinarily there would be many more.
FIG. 2 is a light source and FIG. 3 is a light distributor which
divides the illumination from 2, more or less uniformly, among all
the optical fibers taking their light input from 3, such as 4, 5,
and 6, etc.
Typically, a length of fiber optic conductor 4' extends from the
connector 10 to the front panel to subassembly 7. Here it is
readily observed visually at 9. It is to be understood that a
colored or other lens may be installed at 9 in order to enhance the
observability of light eminating from 9. A typical second pair of
fiber optic connectors, generally at 27 and associated with
subassembly 8 in the same way, is shown in FIG. 1. The numeral 26
generally represents slide rails or the like to guide subassembly 7
into place as it is installed. This ensures that the mating and
disengagement of electrical and fiber optic connectors is the
result of a straight translational movement devoid of rotation or
lateral components of motion insofar as possible.
Referring now to FIG. 2, a typical pair of mating fiber optic parts
suitable for employment in FIG. 1, shows connector parts 10 and 11
in pictorial detail, with associated fiber optic cables 4 and 4',
respectively. If 10 is generally referred to as the pin body, and
11 the socket or receptacle body, it is to be understood that this
refers to the fiber optic elements within each 10 and 11, however,
from the connector shell or housing point of view, 10 might also be
referred to as a socket body and 11 the pin body since the split
end portion 10a receives the solid extension 11a of 11. Fiber optic
conductors 4 and 4' are shown for correspondence to FIG. 1, it
being understood, of course, that the additional fiber optic
connector pair such as generally shown at 27 in FIG. 1, and all
others in a given arrangement would typically be identically
arranged.
Referring now to FIG. 3, fiber optic connector parts 10 and 11 are
shown in their fully mated condition in which the optical fiber 4
associated with 10 is fully interfaced at 30 with the fiber optic
conductor 4' associated with 11. The nose 11a is shown inserted
into 10a, this corresponding to essentially a full mating of 10 and
11 and of the respective subassembly into the corresponding rack
position. The sectioned panels 12 and 13 represent corresponding
typical structural members in 7 and the rack 1, respectively,
although it should be understood that the converse arrangement is
readily possible. Also, the manner in which 10 and 11 are anchored
to the respective subassembly and rack structure are subject to
much variation within the realm of ordinary mechanical skill, and
the representation of FIG. 3 in that regard is to be considered as
suggestive only.
The connector body 10 will be seen to contain two axial bores in
addition to the socket space within 10a, these being 14 and 32.
Bore 14 is the larger of the two and contains an internally
threaded portion 16 engaging corresponding threads on gland nut 18.
A gland seal is comprised of O-ring parts 20, 21 and 22, which are
made of a resilient plastic or rubber-like material having a
suitable bulk modulus. An axial bore 18a through the gland nut 18
and through which the fiber optic element 4 passes is understood to
be a clearance hole with respect to the outside diameter of 4.
Advancement of the gland nut 18 compresses the gland seal members
causing them to firmly grip the fiber optic element 4.
The same basic arrangement pertains in respect to connector part
11, i.e., that it has a gland nut 19 threading into the threaded
portion of internal bore 15 at 17, likewise capable of being
advanced to compress the gland seal provided by O-rings 23, 24 and
25 to grip the optic fiber 4', holding it in place axially.
Both optical fiber elements (namely, 4 and 4') are protected by
typical termination pins or ferrule members 28 and 29,
respectively. These members protect the optical fibers against
breakage or mechanical damage and are common in the fiber optic
connector art, such termination pins or ferrules are shown in the
prior art, for example, in U.S. Pat. Nos. 3,914,015 and
3,947,182.
Unlike the bore 32, bore 33 is partially bottomed at 36, and it is
intended that the presetting of gland nut 19 during manufacture
should establish the interface point 30, i.e., the leftmost
extremity of the optic fiber 4'. In this way, the flexible
diaphragm 31 is held in place about its outer perimeter by the nose
piece 11a which is firmly attached to connector body 11 along the
press-fit interface 37.
it will be realized that typical fiber optic conductors or cables,
even if composed of a number of paralleled strands of optical
fiber, are relatively small in size (diameter). Thus, the showing
of FIG. 3 will be recognized as exaggerated in size, this being
necessary for clarity of description.
Of course, rather than being a press-fit, the interface 37 might be
a threaded engagement or other type of joint. The extremity of the
nose piece 11a also includes a concentric bore chamfered at 38 for
guidance of the extremity of the termination pin 28 containing
optical fiber 4.
At this point, it is desirable to also consider FIG. 4. Here, the
flexible (slit) diaphragm is shown in its flat axially viewed form
in order to have a clear understanding of its construction.
Essentially, it is a disc of a resilient flexible material as
aforementioned, containing slits 39a-39e producing a plurality of
radially inwardly extending fingers which are readily parted by
passage of 28 therethrough. Since, as hereinbefore indicated, the
actual sizes of the components represented in FIG. 3 are
considerably smaller than illustrated, the axially measured
distance between initial engagement of 28 against 29 and full
engagement of 29 against the interface 30 is relatively small. It
will be realized that some light transmission will occur between 4
and 4'as the diaphragm 31 is penetrated but before 29 reaches the
interface 30. Good design in this regard would indicate that this
final engagement distance from initial penetration of 31 to the
full engagement at interface 30 should represent a range of
acceptable degrees of mating of the electronic subassembly (7, for
example) into the rack 1 (FIG. 1) so that the electrical connectors
at 34 and 35 are satisfactorily mated over that range.
As an installation adjustment, for the selection of the on/off
sequence, gland nut 18 may be backed off, freeing the optical fiber
4 to be positioned axially so that the penetration of the diaphragm
31 occurs during the final axial increment of electrical connector
engagement (for example, 0.15 to 0.02 inches approximately).
Suitable materials for the connector halves and their integral
parts are well known in the fiber optic connector art. Still
further, there are a number of possibilities for the construction
of the light distributor 3 illustrated in FIG. 1. The arrangement
shown in U.S. Pat. No. 3,638,008 is one suitable arrangement for 3
of FIG. 1. Actually, 2 and 3 of FIG. 1 would be combined in such an
arrangement.
It will be evident, of course, that individual light sources at the
alignment locations within the rack 1 could be used. However, such
a change would detract from the basic reliability and convenience
of the preferred embodiment herein described. With the single light
source and fiber optic conductors therefrom, as shown and
described, the possibility of failure of the light source can be
ruled out in respect to the mating of an individual electronic
subassembly to the rack if the fully mated light indication on the
panel of the electronic assembly is not observed while the same
indications for others of the subassemblies are evident.
Although the structure described in the overall sense involves a
fixed rack position and a movable subassembly, it will be readily
evident that two portable or separately movable "black box" devices
could employ the same structure for the same purpose with a minimum
of adaptation, to confirm an electrical or even an entirely
mechanical "mate-up".
Various other design modifications are possible within the spirit
of the present invention and, accordingly, it is not intended that
the scope of the invention should be considered limited by the
drawings or this description, these being intended to be typical
and illustrative only.
* * * * *